The invention concerns more particularly the method of fixing the outer lens to the housing. It is known how to provide, along the edge of the housing where the outer lens is to be fixed, what is referred to as a bonding groove, which defines a channel intended to receive a so-called structural adhesive, that is to say an adhesive which has a dual property: the property of providing the watertightness of the device in all its forms, and the property of effectively fixing the outer lens to the housing. This type of adhesive is deposited in the groove in the form of a paste of appropriate viscosity, and the edge of the outer lens is then disposed in the groove, so that it is entirely covered by the adhesive on its edge and its two faces, over a sufficient height. The adhesive then has a few minutes to harden, and finally to fix the glass definitively.
However, this lapse of time, between the moment when the outer lens is disposed in the bonding groove and the moment when the adhesive has hardened, is a tricky period: this is because it is necessary for the outer lens to be initially correctly positioned in the groove and for it to keep its correct positioning until the adhesive is hardened. For this purpose, recourse may be had to support and positioning means provided on the housing and/or on the outer lens: for example, at the foot of the outer lens (the “foot” of the outer lens being the area of the outer lens intended to be fixed to the housing) a protuberant area is provided which cooperates with one of the edges of the bonding groove of the housing. It has turned out that this type of means could prove to be insufficient.
There is known from the patent U.S. Pat. No. 6,478,451 a method of fixing the outer lens to the housing where there is no bonding groove on the housing: the shape, for example in a bevel or in a point with two facets, of the edge of the outer lens is adapted to the complementary shape of the edge of the housing to which the outer lens is to be fixed. Then the edge of the glass is welded by radiation to the edge of the housing whilst simultaneously exerted a mechanical pressure between outer lens and housing in the junction area of the two parts. However, this technique is not devoid of drawbacks: it requires laser treatment along the whole periphery of the housing if it is wished to ensure watertightness of the housing, which may take too long. It also requires good chemical compatibility between the outer lens and the housing, and mechanical press means to be positioned precisely. It is not certain that it is thus possible to ensure, after treatment, perfect watertightness at the outer lens/housing junction, even if the mechanical fixing is ensured.
The aim of the invention is then a novel method of fixing the outer lens on the housing of a lighting and/or signaling device for a vehicle, which is better, and which is in particular more reliable than in the known technical solutions, which guarantees in particular better positioning of the outer lens during the bonding proper, and/or which simplifies the fixing operation or the design of the elements to be bonded.